cobrajet

HI, new member here. I just bought a 1996 Jeep Grand Cherokee Limited. The engine was blown up so I transplanted one from a donor. It runs really good now. Just have one problem. The battery will drain down after a couple of days. Read thru some of the post about a bcm going bad can cause a drain with switch off. So I found mine and disconnected the white plug the test light on the negative terminal went out. Should I get another bcm or keep looking? Also when I pull the fuse for the instrument panel the test light goes out. Any suggestions would be greatly appreciated before I start parts buying and gambling?

ol"blue

I'm not sure on the electrical issues. Other more knowledgeable people will chime in I'm sure. seed is the ZJ guru. Willys55 is too.
And Welcome to CF.

Cherokee 4.0

offsite email and ill email diagrams

Willys55

Hi Cobrajet,...................before you go bananas looking for the drain. How old is the Battery? Have you tested the battery? Test light does aid when looking for draw but it can not tell you just how many amps you are pulling. If you have access to a multi meter with an amp probe just place the amp probe over the postive lead at the battery and read the amps. If you have less than 1.6amp draw stop looking and clean your grounds and battery terminals, also check that alternator is providing the correct charge. Verify your batteries integratity as well. Keep us posted as to what you find or even pm me if you like.. Welcome to CF

cobrajet

Hi, battery is new. Took the altenator to autozone they checked it said it was fine. I checked the output voltage on altenator and if I remember it was around 14 volts. Havent done a amp draw chk thou.

Willys55

When you have the probe hooked up....pull one fuse at a time and note the change in amperage. If little or no change put that fuse back and move on to the next one. Check your fuse panel description and start with the fuses that are prone to draw, for example.....ECM, PCM, starter, alternator, power door locks, power seat, power windows.......
Starters have been know to cause 3 amp draws when the windings begin to fail. Power seats are also notorious.

cobrajet

I went out to the garage to chk amp draw on battery, discovered my meter only measures amps in ac not dc. So I pulled the positive cable off and connected my meter between the cable and post. Set it to dc voltage. Its reading 11.5 volts. Somethings going on. Put my test light on again between the negative cable and post it lit right up. Also noticed light somewhat pulsates. If I remember right some cars have a voltage regulator on back of instrument panel that reduces voltage to 6v. This v-regulator pulsates back and forth. I quess Ill go to Sears and get me a meter that reads dc amps. Im always looking for a excuse to buy a new tool.